1. Field of the Invention
The present invention is directed to an improved fuel delivery device for delivering fuel from a reservoir to an internal combustion engine.
2. Description of the Prior Art
A device for delivering fuel is already known from DE 195 27 134 A1, in which a check valve and a pressure outlet valve are situated parallel to each other in a valve housing; the flow travels through the pressure outlet valve in the opposite direction from that of the check valve. When a fuel-supply pump is operating, it delivers fuel via the check valve into a fuel rail; once the fuel-supply pump has been switched off, the check valve maintains the pressure in the fuel rail. If a pressure increase in the fuel rail occurs due to a heating of the device after the engine is switched off, then the pressure outlet valve opens, permitting fuel to flow back into the tank. The disadvantage to this is the insufficient control precision, particularly at low volumetric flows.
DE 197 05 405 A1 has disclosed a diaphragm valve with a high degree of control precision. The diaphragm valve has a first chamber and a second chamber, which is separated from the first chamber by means of a valve member; the valve member cooperates with a valve seat; and a first connecting conduit in the vicinity of the valve seat feeds into the first chamber. The disadvantage here is that the diaphragm valve cannot be used as a pressure outlet valve without being modified because it opens toward the fuel rail in the same was as the check valve during operation of the fuel-supply pump.